Can the Samur Eye be Painted

According to an interesting forum post describing the advantage of the degreaser, the default switch time is 0.67 seconds.

As far as I know only the Degreaser (65% faster, 0.67(1-0.65) = 0.2345 seconds) and Reserve Shooter (15% faster, 0.67(1-0.15) = 0.5695 seconds) can affect this, besides the weapon-specific limitations as mentioned in Toomai's answer. Also of course the Half-Zatoichi is 'honorbound' and has a switch time as long as it takes you to get a kill!

Paint will not necessarily increase the value of a hat for a potential buyer, and very well may make it much harder to sell said painted hat. Certain colors are more desired than others, mostly the ones that cannot be found through random drops, e.g. black, white, team colors, after eight, mann's mint, pink as hell, and lime.

In general, you would likely get more value selling the paint separately, and it would be much easier to sell than finding someone who wants both the hat and the color together.